Sulfonium and Selenonium Salts as Noncovalent Organocatalysts for the Multicomponent Groebke–Blackburn–Bienaymé Reaction

Abstract

Sulfonium and selenonium salts, represented by S-aryl dibenzothiophenium and Se-aryl dibenzoselenophenium triflates, were found to exhibit remarkable catalytic activity in the model Groebke–Blackburn–Bienaymé reaction. Kinetic analysis and density functional theory (DFT) calculations indicated that their catalytic effect is induced by the ligation of the reaction substrates to the σ-holes on the S or Se atom of the cations. The experimental data indicated that although 10-fold excess of the chloride totally inhibits the catalytic activity of the sulfonium salts, the selenonium salt remains catalytically active, which can be explained by the experimentally found lower binding constant of the selenonium derivative to chloride in comparison with the sulfonium analogue. Both types of salts exhibit lower catalytic activity in the model reaction than dibenziodolium species.

Halonium, chalconium, and pnictonium salts as noncovalent organocatalysts: a computational study on relative catalytic activity

“…In the case of the nucleophilic addition of ammonia to the carbonyl group (TS2), the total electronic energy of activation is reduced for 1-9 from −11 kJ mol Although the experimental data on the relative catalytic activity between the ChB-and XB-donating organocatalysts are scarce, the computational results obtained by Method 2 seem to be more coherent with our recent works on the experimental determination of the catalytic activity of onium salts. 68,71 Thus, it has been found for the Groebke-Blackburn-Bienaymé multicomponent reaction including the electrophilic activation of the carbonyl group that the iodonium salt 9 OTf exhibits significantly higher catalytic activity than the selenonium salt 5 OTf , which, in turn, provides a slightly higher catalytic effect than the sulfonium salt 4 OTf . 55,68,71 In addition, Yoshida and his co-workers have shown that iodonium salts exhibit a significantly higher catalytic effect than bromonium and chloronium salts 55 (see Fig.…”

“…68,71 Thus, it has been found for the Groebke-Blackburn-Bienaymé multicomponent reaction including the electrophilic activation of the carbonyl group that the iodonium salt 9 OTf exhibits significantly higher catalytic activity than the selenonium salt 5 OTf , which, in turn, provides a slightly higher catalytic effect than the sulfonium salt 4 OTf . 55,68,71 In addition, Yoshida and his co-workers have shown that iodonium salts exhibit a significantly higher catalytic effect than bromonium and chloronium salts 55 (see Fig. 4, energy diagram for Method 2).…”

“…Thus, it has been shown that telluronium salts E (Ch = Te IV ) exhibit a sig- nificantly higher Lewis acidity compared to tellurium(II) derivatives B and lighter chalcogen(IV)-derived species, 65,66 whereas selenonium salts E (Ch = Se IV ) are better catalysts than their sulfonium analogues E (Ch = S IV ). 67,68 Nevertheless, sulfonium salts do exhibit sufficient catalytic activity towards a series of model organic transformations. 68,69 Although PnB donating organocatalysis is still in its infancy and requires additional investigation, it was shown that stibonium(V) derivatives D can be used as Lewis acids for the catalysis of some organic reactions.…”

“…67,68 Nevertheless, sulfonium salts do exhibit sufficient catalytic activity towards a series of model organic transformations. 68,69 Although PnB donating organocatalysis is still in its infancy and requires additional investigation, it was shown that stibonium(V) derivatives D can be used as Lewis acids for the catalysis of some organic reactions. [15][16][17][18] These promising results on the high catalytic activity of pnictogen(V), chalcogen(IV), and halogen(III) derivatives (D, E, F, respectively) allow a suggestion that the extension of a series of organocatalysts to noble gas(II) derivatives would cast light on new efficient organocatalysts based on aerogen bond donating species.…”

“…Thus, it has been shown that telluronium salts E (Ch = Te IV ) exhibit a significantly higher Lewis acidity compared to tellurium( ii ) derivatives B and lighter chalcogen( iv )-derived species, 65,66 whereas selenonium salts E (Ch = Se IV ) are better catalysts than their sulfonium analogues E (Ch = S IV ). 67,68 Nevertheless, sulfonium salts do exhibit sufficient catalytic activity towards a series of model organic transformations. 68,69…”